Heretofore, as a method for manufacturing propylene, generally employed is a steam cracking method for naphtha, or a fluid catalytic cracking method for vacuum gas oil. The steam cracking method produces a large quantity of ethylene in addition to propylene, in which it is difficult to significantly change the production ratio of propylene to ethylene and it is therefore difficult to meet the supply-demand balance of propylene and ethylene. Accordingly, a technique is desired for manufacturing propylene at a high yield from ethylene alone as a starting material.
Regarding the technique, Patent Reference 1 discloses a method for manufacturing propylene from ethylene as a starting material, in which an aluminosilicate catalyst having a pore size of less than 0.5 nm is used. According to the method, propylene can be produced efficiently from ethylene.
In hydrocarbon conversion reaction, in general, the catalyst is deactivated by coke deposition thereto. The same shall apply also to the reaction of producing propylene form ethylene, in which, therefore, coke must be removed for catalyst regeneration. In general, the deposited coke is burnt and removed away with a gas comprising oxygen.
In Patent Reference 2, a zeolite-β catalyst deactivated in aromatic alkylation reaction is regenerated by oxidizing the deposited coke with an oxygen-containing gas.
In Patent Reference 3, for regenerating the catalyst used in fixed bed vapor-phase reaction, an oxygen-containing vapor is circulated through the system for coke removal.